Title (de)

Title (fr)

Publication

Application

Priority

FR 9910798 A 19990826

Abstract (en)

The frequency synthesizer comprises a block (13) for the determination of real gain of voltage-controlled oscillator (1) on the basis of measured parameters, voltage and frequency, and the delivery of signal representative of real gain. The synthesizer also comprises means for an input of modulation signal between the phase comparator (7) of the phase-locked loop (PLL) and the modulation branch (34) with a divider (38) by real gain (KVCO), a digital-analogue converter (40), and an adder (42). A compensation block (50) generates a signal on the basis of modulation signal for input to the feedback loop (9) upstream of divider (8) by N, in a manner to annul the modulation of signal at the output of voltage-controlled oscillator. The sythesizer also comprises a local oscillator (3) connected to one input of the phase comparator (7), the other input connected to the output of voltage-controlled oscillator via the feedback loop (9), and a low-pass filter (5). The gain determination block (13) contains a sampler (15) for voltage measure at two frequencies, an analogue-digital converter (17), and a computing unit (19) for the computation of real gain (KVCO) of voltage-controlled oscillator (VCO). The block (13) also comprises a temperature sensor, a memory table of VCO gain as a function of temperature, and a control unit for the delivery of real gain of VCO as a function of measured temperature and the gain values stored in memory table. The block (13) also function of operating time, and a control unit for the delivery of real gain of VCO as a function of multiplier (52) by 2.pi, an accumulator (54), I and Q (in-phase and quadrature) signals generator (56), first and second digital-analogue converters (58,60) for I and Q signals, respectively, mixers (62,64), a phase-shifter (66) by pi/2 of VCO output signal, and an adder (68).